Balanced slide-valve



Patented May 22,1883.

S. E. JARVIS.

BALANGED SLIDE VALVE.

(No Model.)

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UNITED STATES PATENT OFFICE.y i,

i SAMUEL E. JARVIS, OF LANSING, MICHIGAN.

BALANCED SLIDE-VALVE.

SPECIFICATION forming npart of Letters Patent No. 278,020, dated May/22, 1883.

Application tiled December 13, 1882. (No model.)

To alt whom it may concern Be it known that I, SAMUEL E. JARVIS, of Lansing, in the county of Ingham4 and State -ot' Michigan, have invented new and useful Improvements inl Balanced Slide-Valves.; and I do` hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to certain new and useful improvements in that class of steam-engine valves known as slide-valves;77 and the novelty consists in the construction, arrangement, and adaptation of parts, as will be more fully hereinafter set forth, and specifically poi-nted out in the claims.

In a patent, No. 267,791, issued to me November 21, 1882, l show a balanceslide-valve which is especially'simple in its application to existing engines, and this same valve and method of balancing I embody in myimprovement, making the same thereby an improvement of the valve described in the abovementioned Letters Patent. A cursory examination of this valve tells the engineer that under its best conditions, and with the steam' cut od at an early part of the stroke, the diagram obtained by the engine will show a decided compression corner, and of course corresponding therewith an equivalent lead upon the eduction side. This evil I remedy by my auxiliary exhaust-valve, as hereinafter shown and described.

Figure l is a cross-section ofthe valve-chest, showing the main and auxiliaryexhaust-valve upon the valve-seat. Fig. 2 .is a longitudinal vertical section on the lille .c m through the main valve. Fig. 3 is asimilar section through the auxiliary exhaust-valve. Fig. 4 is a diagram section ot' the two valves with the cylinder parts between them, so as to readily show 'their respective laps.

In the accompanying drawings, A represents the-main slide-valve, intended to be operated by a variable cut-off in the usual manner. B is the auxiliary exhaust slide-valve operated by an independent eccentric. (Not shown.) C is the cylinder; I), the piston. F and G are the steam-inlet ports. H is the exhaustport. I is the valve-chest. K is a saddle,

' the oice ot' which is to balance the valve in connection with the relief-ports L, M, N, and P in the valve A, and is fully explained in the aforementioned Letters Patent. R, S, and T are relief-ports in the exhaust slidevalve B, which likewise act in combination with the saddle K to balance the valve.

v In Fig. 4, a, b, c, and d show the lap ot' the valve A on the` steam side, and e,j`, g, and lt on the exhaust side, the latter being suiiicient, as shown in Fig. l, to keep the eduction-port behind the piston closed until the stroke is completed. This valve is set without any lead whatever, making its action perfectly alike at either end ot' the stroke. The exhaust slide-valve B has the lap t, k, l, and m upon the steam side sufficiently large to keep the steam-ports F and G constantly closed. On the exhaust side it has no lap. The Lsteam-valve'is set with the usual lead, so as to open the induction-port behind the piston before the stroke is nearly completed, as shown in Fig. 2. In Fig.l, where both valves are shown in cross-section, they are of even width; but I do not intend to contine myself to their relative dimensions, as I may use a much smaller exhaust-valve, making themain valve correspondingly larger. No injurious effects are produced by restricting the induction-ports to the width ot the valve A, as by vthe interiorconnections,T and IV, between the relief-ports L and M, as shown, the steam is enabled to enter virtually through the four ports at once. The valves A and B have precisely the same thickness, and the saddle K, forming the means of balancing the valve A, also balances the valve B, as the latter valve is affected on its lower side by the same pressures, and the relief-ports R,- T, and S in this valve are only additional means to establish the equilibrium on both sides more readily. It will be seen that the balancing of my valve is inseparably connected with its proper function as a valve. v

What I claim as my invention isl. Acompound slide-valve composed of a main slide-valve, occupying one-halt' or more of the seat, and having additional steam-ports,

.as L and M, and internal connections, as V and W, and an auxiliary exhaust-valve actuated by an independent eccentric, the said valves being balanced by a single means common to both, and the Whole combined and arranged to operate substantially as set forth.

2. "A compound balanced slide-valve, con` sistiug ot' the main valve A, with its relief'- ports, an auxiliary exhaust-valve actuated by an independent eccentric, and provided with necessary lap, in combination with the saddle K, which forms a counterpart of thevalve- 1o seats, substantially as and for the purpose described. Y

SAMUEL E. JARVIS. Vitnesses H. S. SPRAGUE,

E. W. ANDREW. 

